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TT: Fachverband Tiefe Temperaturen

TT 14: Superconductivity: Non-Cuprate Non-Ferropnictide Superconductors

TT 14.8: Vortrag

Dienstag, 24. März 2009, 11:45–12:00, HSZ 105

Functional renormalization for antiferromagnetism and superconductivity in the Hubbard model — •Simon Friederich — Institut fuer Theoretische Physik, Universitaet Heidelberg

Results of a renormalization group study for the 2-dimensional Hubbard model close to half-filling at finite temperature are presented. Bosonic degrees of freedom corresponding to antiferromagnetic and d-wave superconducting order are introduced, and flow equations for the corresponding coupling constants are deduced from an exact flow equation for the effective average action.

The influence of bosonic fluctuations on the onset of local antiferromagnetic oder is discussed. At low enough temperatures and close to half-filling the discrete symmetry of the lattice is broken and incommensurate antiferromagnetic fluctuations dominate. The phase diagram is shown for the parameter regime close to half-filling in the presence of vanishing as well as non-vanishing next-to-nearest-neighbor hopping t'.

Finally, the potential emergence of d-wave superconducting order at larger distances from half-filling is discussed.